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Supplemental Guidance - Use of Disinfectants and Sanitizers in Heating, Ventilation, Air Conditioning, and Refrigeration (HVAC&R) Systems

September 30, 2010

The purpose of this guidance is to supplement the March 14, 2002 letter from Marcia Mulkey, former Office of Pesticide Programs Office Director at the EPA, which identified several Agency concerns regarding the use of sanitizers, disinfectants and other types of antimicrobial products to treat the surfaces of heating, ventilation, air conditioning and refrigeration (HVAC&R) systems, typically as part of air duct maintenance or cleaning. The intent of the supplemental guidance is to ensure that users, applicators and registrants are only using products labeled for use in HVAC&R systems. The Agency is providing this supplemental information because HVAC&R systems represent a unique use site and the Agency concerned about potential risks to applicators and building occupants that may be associated with the use of antimicrobial products in such settings.

The Agency believes that certain types of antimicrobial products not registered for use in HVAC&R systems are being used in a manner not authorized by the label and not assessed by the Agency as part of the pesticide registration or amendment process. Although the directions for use of most registered sanitizer and disinfectant products permit use on hard non-porous surfaces, because of the uniqueness of HVAC&R systems, such directions for use do not include use on or in HVAC&R components or surfaces unless such HVAC&R use is specifically included on the label.

Unique Use Site and Exposure

The Agency believes that application of an antimicrobial product to an HVAC&R system represents a use pattern that is substantially different from other hard surface disinfection or sanitizer uses. First, an HVAC&R system needs to be inspected cleaned and/or duct work needs to be repaired to ensure that the system is in sound mechanical condition prior to treatment with an antimicrobial product. These specific label instructions are not found on a typical antimicrobial product. Second, the methods used to treat HVAC&R systems, as well as the application equipment used, are substantially different from those found on the label of a typical antimicrobial product that may be applied to hard non-porous surfaces. Many antimicrobial products are applied to hard surfaces as either a ready-to-use spray or as a diluted liquid using a sponge, towel or other means to spread the material over the surface. An HVAC&R system application is often made using an Ultra Low Volume (ULV) or mist generating sprayer or through the use of an automated spraying system sometimes carried by robots through air ducts. These methods of application are substantially different from the conventional use of antimicrobials to treat hard non-porous surfaces. Finally, many of the components of HVAC&R systems are typically inaccessible, which could create unique exposure scenarios for applicators, and label directions responsive to such considerations are not found on the label of a typical antimicrobial product.

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Risk Assessment and Registration

The Agency needs to conduct a risk assessment before it can decide whether an applicant for registration (or amendment to a registration) can include HVAC&R system use on the product label. In the absence of adequate data to enable appropriate review and evaluation of these products, it is possible that use of these products in HVAC&R systems could lead to significant exposures in indoor environments with potentially unreasonable adverse effects. Agency review and assessment of a HVAC&R system use may identify mitigation measures (e.g., label changes) that may be required if risk concerns are identified. In addition, the Agency’s risk assessment will help ensure that the most sensitive populations, such as infants and children, will not be negatively impacted from pesticides that are used to treat HVAC&R systems.

To support an application for such a registration or amendment to a registration, adequate and appropriate directions for HVAC&R system use should be submitted and include specific proposed directions for use addressing the following:

If a public health claim is made, such as a sanitizer or disinfectant claim for duct work, then efficacy data must be submitted to support the proposed claim. In such a case, the Agency may need to review a protocol prior to submission of a registration application. Among other things, the protocol would have to address how the product will be applied to ensure that all the duct work will be treated. In addition, the protocol would need to address how the surface will remain wet for the required product contact time.

The Agency encourages a pre-registration meeting for those interested in registering a product for HVAC&R system uses or for adding this use to a previously registered product label.


Direct questions to Tracy Lantz at (703)308-6415.

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